In recent years, information providing services using the Internet are available upon preparing communication infrastructures and developing information communication techniques. The information providing services using the Internet can provide multimedia information including images and sounds as well as information using letters.
A user who receives an information providing service via the Internet registers a mail account for using electronic mail and can perform communication using electronic mail and exchange information with other users.
Electronic mail information is generally represented by text. However, a binary file such as application data (document file) prepared by a user can be attached to electronic mail information by a technique for encoding the binary file into text data and a technique for decoding encoded text data.
The radio communication infrastructures have been prepared, and information communication techniques have been developed. In addition, terminals using these infrastructures and information communication techniques have been downsized. Mobile portable terminals such as portable telephones as well as desktop personal computers can be connected to the Internet. As a result, users using electronic mail with portable terminals have abruptly been increasing.
A means for acquiring information circulated in the Internet is not limited to a personal computer but can extend to a portable terminal and electronic mail terminal. These terminals have a variety of limitations such as the limitation of receivable information quantity, the limitation of display capacity of a terminal such as a display size, color, and resolution, the unique physical limitation, and the unique limitation on capacity.
Under these circumstances, unless information communication is performed upon understanding the environments of the sender and recipient in advance, reception information which cannot be processed on the receiving side cannot be received and is hence discarded.
Communication using electronic mail with a portable terminal via the Internet is allowed. However, if a mail recipient does not notify a mail sender of limitations on information contents (e.g., attachment of a computer electronic file or binary file) and the number of characters processed per mail, information which cannot be properly received (discarded before arrival of mail to the terminal) by the recipient may be generated.
Some portable terminal mail addresses can make a user imagine that it is a portable terminal depending on its domain name. However, the portable terminal mail address belongs to a standard Internet mail address system. Some portable terminal users use as a portable terminal mail address a mail address used at a terminal (e.g., a desktop personal computer) having electronic mail reception limitations different from those of the portable terminal. A transmitting side cannot easily decide the information reception capacity of the recipient terminal. It is, therefore, very difficult for an electronic mail sender to predict the recipient environment and send information processed to be received by the recipient.
Electronic mail messages from which information is omitted are frequently transmitted via portable terminals at the present. Users have no choice for any means for avoiding this.
To avoid the above situation, a technique has already been available, in which electronic mail to a portable terminal is transferred to one account on a World Wide Web server before reception of the mail at the portable terminal, and the mail is browsed via the World Wide Web mechanism. This technique cannot cope with browsing a binary file or acquiring data although the limitation on the number of receivable characters at a portable terminal is canceled.
Assume that an electronic mail sender attaches a document file or the like prepared using any application. In this case, a user using only the portable terminal as an Internet connection means may not be able to browse this document due to the limitations on the display capacity of the portable terminal.
To map and display document information attached to electronic mail, even an Internet connection terminal having almost no limitations as a reception means such as a desktop personal computer in addition to a portable terminal requires an application used when a sender prepares an attached document to electronic mail and sends it to a mail receiving terminal, or an application compatible with the above application. Such an application or compatible application is not always present in the electronic mail receiving terminal. When the electronic mail receiving terminal does not have the application used when the sender prepares the attached document or the application compatible with it, the recipient cannot easily observe the information transmitted by the electronic mail sender.
Under these circumstances, the recipient cannot check information sent from the sender unless the recipient prepares with much labor an environment compatible with the transmission environment of the sender.